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541.
The diversity of bacteria metabolizing nitriles of carbonic acids was studied in soils of the Perm region affected by human activities. Effective methods for selective isolation of cultures possessing the nitrile hydratase and nitrilase activities were developed. Most microorganisms capable of utilizing nitriles were Grampositive Nocardia-like bacteria of the genus Rhodococcus. Isolates with a detectable nitrilase activity were also represented by Gram-negative forms (Gram-negative aerobic/microaerophilic bacilli and cocci of the genera Pseudomonas, Azomonas, Azotobacter, and Acidovorax). Two enzyme systems for nitrile hydrolysis were found in 27% of cultures. The nitrile hydratase and nitrilase activities of the studied strains exceeded these enzymatic activities in bacteria isolated from native soils, which indicates that natural selection of saprophytic microflora occurs in chemically altered soils.  相似文献   
542.
本文旨在通过聚合酶链反应PCR、构建克隆文库、15N同位素示踪等技术研究厌氧氨氧化细菌在以天山天池为代表的高海拔低温水生态系统中的存在、发生、活性及对氮循环的影响.通过定量PCR测得天山天池沉积物厌氧氨氧化菌的丰度为(2.93×105±0.25×105)copy/每克干沉积物土样,证明了存在有一定数量的厌氧氨氧化菌;在分别对厌氧氨氧化细菌的16S rRNA和hzs B功能基因构建克隆文库,并对阳性克隆进行生物多样性分析,发现天山天池沉积物中16S rRNA阳性克隆子均属于同一个独立操作单元,与已知的厌氧氨氧化菌的相似度高于99%;而hzs B功能基因克隆文库中,其生物多样性略高于16S rRNA文库.通过同位素示踪技术测得该样品的厌氧氨氧化速率为1.162 nmol·g-1·h-1,其对氮气生成的贡献率高达82%,远高于以往报道的淡水环境中厌氧氨氧化对氮气生成的贡献率.推断高海拔和低温等环境可能不是限制厌氧氨氧化细菌生长的关键因素.  相似文献   
543.
With the aim of wood production with negligible negative effects on biodiversity and ecosystem processes, a silvicultural practice of selective logging with natural regeneration has been implemented in European beech forests (Fagus sylvatica) during the last decades. Despite this near‐to‐nature strategy, species richness of various taxa is lower in these forests than in unmanaged forests. To develop guidelines to minimize the fundamental weaknesses in the current practice, we linked functional traits of saproxylic beetle species to ecosystem characteristics. We used continental‐scale data from 8 European countries and regional‐scale data from a large forest in southern Germany and forest‐stand variables that represented a gradient of intensity of forest use to evaluate the effect of current near‐to‐nature management strategies on the functional diversity of saproxylic beetles. Forest‐stand variables did not have a statistically significant effect on overall functional diversity, but they did significantly affect community mean and diversity of single functional traits. As the amount of dead wood increased the composition of assemblages shifted toward dominance of larger species and species preferring dead wood of large diameter and in advanced stages of decay. The mean amount of dead wood across plots in which most species occurred was from 20 to 60 m3/ha. Species occurring in plots with mean dead wood >60 m3/ha were consistently those inhabiting dead wood of large diameter and in advanced stages of decay. On the basis of our results, to make current wood‐production practices in beech forests throughout Europe more conservation oriented (i.e., promoting biodiversity and ecosystem functioning), we recommend increasing the amount of dead wood to >20 m3/ha; not removing dead wood of large diameter (50 cm) and allowing more dead wood in advanced stages of decomposition to develop; and designating strict forest reserves, with their exceptionally high amounts of dead wood, that would serve as refuges for and sources of saproxylic habitat specialists. Efectos Actuales del Manejo Casi Natural de Bosques sobre la Composición de Atributos Funcionales de Escarabajos Saproxílicos en Bosques de Haya  相似文献   
544.
Abstract:  Questions persist regarding whether the science of conservation biology can successfully affect environmental decision making. One of the most prominent fields of intersection between conservation science and environmental policy is public-lands debates in the United States. I reviewed the role of conservation science in the roadless-area policies of the U.S. Forest Service. Since 1971, the Forest Service has systematically evaluated roadless areas on national forests three times, most recently during the Clinton administration's Roadless Area Conservation Review (1998–2000) ( U.S. Department of Agriculture Forest Service 2000b ). Drawing on the agency's environmental impact statements and supporting documents and the internal records of conservation organizations, I examined the changing goals, methodology, and outcome of roadless-area advocacy and policy. Since the 1970s, conservation science has successfully informed public and administrative concern for roadless-area protection. Conservation science has transformed public discourse regarding roadless areas and has changed the scope and rationale of national conservation organizations' goals for roadless-area policy from protecting some to protecting all remaining national forest roadless areas. The Forest Service has increasingly drawn on the lessons of conservation biology to justify its methodology and its administrative recommendations to protect roadless areas. The 2000 Roadless Area Conservation Review resulted in a recommendation to protect all remaining national forest roadless areas, up from 22% of roadless areas in the first roadless review. Despite the scientific merits of recent roadless-area advocacy and policy, however, such initiatives have faced political difficulties. The emphasis on large-scale, top-down, national approaches to conservation policy has rendered such policies politically problematic.  相似文献   
545.
Abstract:  The task of measuring the decline of global biodiversity and instituting changes to halt and reverse this downturn has been taken up in response to the Convention on Biological Diversity's 2010 target. It is an undertaking made more difficult by the complex nature of biodiversity and the consequent difficulty in accurately gauging its depletion. In the Living Planet Index, aggregated population trends among vertebrate species indicate the rate of change in the status of biodiversity, and this index can be used to address the question of whether or not the 2010 target has been achieved. We investigated the use of generalized additive models in aggregating large quantities of population trend data, evaluated potential bias that results from collation of existing trends, and explored the feasibility of disaggregating the data (e.g., geographically, taxonomically, regionally, and by thematic area). Our results show strengths in length and completeness of data, little evidence of bias toward threatened species, and the possibility of disaggregation into meaningful subsets. Limitations of the data set are still apparent, in particular the dominance of bird data and gaps in tropical-species population coverage. Population-trend data complement the longer-term, but more coarse-grained, perspectives gained by evaluating species-level extinction rates. To measure progress toward the 2010 target, indicators must be adapted and strategically supplemented with existing data to generate meaningful indicators in time. Beyond 2010, it is critical a strategy be set out for the future development of indicators that will deal with existing data gaps and that is intricately tied to the goals of future biodiversity targets.  相似文献   
546.
Abstract:  For many regions worldwide, multiple and often contrasting biogeographic classifications exist that are derived from a variety of taxa and techniques. This presents a challenge for managers who must choose appropriate large-scale spatial frameworks for systematic conservation planning. We demonstrate how systematically collected community data can be used to evaluate existing biogeographic classifications, identify the most appropriate metric for biogeographic patterns seen in other taxonomic groups, and develop an independent biogeographic classification scheme for systematic conservation planning. We evaluated 6 existing biogeographic classifications for New Zealand's nearshore marine environment with community-similarity metrics derived from abundance and presence–absence data for macroalgae (107 species) and mobile macroinvertebrates (44 species). The concordance between community metrics and the previous classifications was high, as indicated by a high multivariate classification success (CS) (74.3–98.3%). Subsequently, we carried out an independent classification analysis on each community metric to identify biogeographic units within a hierarchical spatial framework. The classification derived from macroalgal presence–absence data achieved the highest CS and could be used as a mesoscale classification scheme in which 11 regional groupings (i.e., bioregions) (CS = 73.8–84.8%) are nested within northern and southern biogeographic provinces (CS = 90.3–98.7%). These techniques can be used in systematic conservation planning to inform the design of representative and comprehensive networks of marine protected areas through evaluation of the current coverage of marine reserves in each bioregion. Currently, 0.22% of the territorial sea around mainland New Zealand is protected in no-take marine protected areas in which 0–1.5% of each bioregion represented.  相似文献   
547.
Abstract: The importance of biodiversity as natural capital for economic development and sustaining human welfare is well documented. Nevertheless, resource degradation rates and persistent deterioration of human welfare in developing countries is increasingly worrisome. Developing effective monitoring and evaluation schemes and measuring biodiversity loss continue to pose unique challenges, particularly when there is a paucity of historical data. Threat reduction assessment (TRA) has been proposed as a method to measure conservation success and as a proxy measurement of conservation impact, monitoring threats to resources rather than changes to biological parameters themselves. This tool is considered a quick, practical alternative to more cost‐ and time‐intensive approaches, but has inherent weaknesses. I conducted TRAs to evaluate the effectiveness of Kruger National Park (KNP) and Limpopo Province, South Africa, in mitigating threats to biodiversity from 1994 to 2004 in 4 geographical areas. I calculated TRA index values in these TRAs by using the original scoring developed by Margoluis and Salafsky (2001) and a modified scoring system that assigned negative mitigation values to incorporate new or worsening threats. Threats were standardized to allow comparisons across the sites. Modified TRA index values were significantly lower than values derived from the original scoring exercise. Five of the 11 standardized threats were present in all 4 assessment areas, 2 were restricted to KNP, 2 to Limpopo Province, and 2 only to Malamulele municipality. These results indicate, first, the need to integrate negative mitigation values into TRA scoring. By including negative values, investigators will be afforded a more accurate picture of biodiversity threats and of temporal and spatial trends across sites. Where the original TRA scoring was used to measure conservation success, reevaluation of these cases with the modified scoring is recommended. Second, practitioners must carefully consider the need and consequences of generalizing threats into generic categories for comparative assessments. Finally, continued refinement of the methodology and its extension to facilitate the transfer of successful conservation strategies is needed.  相似文献   
548.
549.
Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement.  相似文献   
550.
Abstract: Discourse around assisted colonization focuses on the ecological risks, costs, and uncertainties associated with the practice, as well as on its technical feasibility and alternative approaches to it. Nevertheless, the ethical underpinnings of the case for assisted colonization are claims about the value of species. A complete discussion of assisted colonization needs to include assessment of these claims. For each type of value that species are thought to possess it is necessary to determine whether it is plausible that species possess the type of value and, if so, to what extent their possessing it justifies assisted colonization. I conducted such an assessment for each of the predominant types of value ascribed to species: ecological, instrumental (including option value), existence, and intrinsic value (including interest‐based, objective, and valuer‐dependent intrinsic value). The vast majority of species, including several that have been proposed as candidates for assisted colonization, have much less value than is often presumed. Moreover, with respect to some types of value, assisted colonization would not fully preserve the value of the target species even if it were to keep the target species in existence. Therefore, the case for assisted colonization is significantly weaker and more qualified than its advocates often suppose. There may be exceptional species for which assisted colonization is well justified—and for this reason, case‐by‐case assessment is necessary—but in general the burden of justification generated by the ecological risks associated with assisted colonization is not met by the value potentially preserved by assisted colonization. This suggests that assisted colonization ought to have, at most, a very minor role in the portfolio of ecosystem management practices, even as it pertains to species conservation under conditions of rapid climate change.  相似文献   
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